The present invention relates to a recording device such as an electrophotographic device or the like including a heating means.
Various heating means are often assembled in a recording device such as an electrophotographic device or the like. For example, in the recording device with the use of a wet-type developer, a heating means is used for the purpose of drying a developer adhered to a recording paper, in the recording device with the use of a dry-type developer, a heating means is used for the purpose of fixing a toner image formed on a recording paper, and in the recording device for transferring a toner image onto a recording paper by means of a heat-transfer roller, a heating means is used for the purpose of heating the transfer roller, respectively. These heating means cannot perform normal operation if they do not have a predetermined operating temperature, so that any normal electrophotographic image or the like cannot be obtained. Therefore, a warming-up time (preheating time) required from the switching-on of an electric power supply source of a heating means to the arrival of a predetermined operating temperature is unavailable for a copying process and becomes a waiting time, but the presence of the warming-up time is unavoidable in the heating means. In general, therefore, while an electric power supply source of a copying device is switched on, it is constructed that an electric power supply source of a heating means is always switched on so as to remove the waiting time. Even in this manner, however, a certain waiting time is always necessary when the power supply source of the copying device is switched on. In the conventional heating means, the warming-up time requires from several minutes to several tens minutes, so that it is very inconvenient to use the heating device, and then it has been tried to shorten this warming-up time in various ways. For example, in Japanese Utility Model Application Publication No. 21,740/74, Japanese Patent Application Publication No. 36,800/70, Japanese Patent Application Publication No. 13,586/76, Japanese Utility Model Laid-Open Publication No. 7,044/75 and the like, there are described that energy of the power supply source at the time of warming-up is made larger than that at the time of usual operation and the warming-up time is made short. In addition to the above, in some improved heating means with various measures, the warming-up time is shortened from several seconds to several tens seconds. However, there is no heating means which can obtain a warming-up time quick enough to be used for a copying process almost simultaneously with the switching-on of an electric power supply source within the range of limited electric power or practical durability. Such measure is, therefore, required that even if the warming-up time of a heating means is as it is, the copying process can be started as quick as possible. In a conventional copying device, an electric power supply source of the device, i.e., the electric power supply source of a heating means, is switched on and the temperature of the heating means reaches a predetermined operating value, and a permission for the start of copying is firstly displayed by detecting this temperature. In practice, however, it takes some time from the start of a copying process to the arrival of material to be heated (recording paper) and during this period, the heating means cannot be used for the copying process. In the conventional copying device, therefore, the waiting time during this period has been useless. There is surely no problem for such a waiting time in the above-mentioned conventional heating means which takes several minutes to several tens minutes for the warming-up time, but a copying device having an improved heating means in which the warming-up time is several seconds to several tens seconds can be shortened its waiting time by eliminating the above useless waiting time.